WADA director general David Howman told reporters that this
defense has been tried in other cases and been rejected. Without
evidence of the contamination, its pretty much impossible for an
athlete to prove that claim.

It also wouldn't explain why another test revealed plastic
residue in the Tour de France winner's blood, which is often a
tell-tale sign of blood doping. The plastic comes from the bags
used in the blood transfusions.

Contador was suspended from cycling last month and his case is
still being investigated.